linux-kernel - Re: [PATCH v2 1/3] nvmem: core: introduce cells parser

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Message-ID: <56fb5c64-4142-03ef-2ea8-fc586fd239e1@linaro.org>
Date:   Mon, 27 Sep 2021 11:12:26 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Vadym Kochan <vadym.kochan@...ision.eu>,
        John Thomson <john@...nthomson.fastmail.com.au>
Cc:     Rob Herring <robh+dt@...nel.org>, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, Robert Marko <robert.marko@...tura.hr>
Subject: Re: [PATCH v2 1/3] nvmem: core: introduce cells parser



On 27/09/2021 08:50, Vadym Kochan wrote:
>>>> Currently I can test only on at24 devices. From the:
>>>>
>>>> https://opencomputeproject.github.io/onie/design-spec/hw_requirements.html
>>>>
>>>> "
>>>> Each ONIE system must include non-volatile storage which contains vital
>>>> product data assigned by the manufacturer. The non-volatile storage
>>>> could take the form of an EEPROM, a NOR-flash sector, a NAND-flash
>>>> sector or any other non-volatile storage medium.
>>>> "
>>>>
>>>> I am not aware about other nvmem devices which are used for existing
>>>> ONIE supported boards.
>>>>
>>>>> As long as you represent this parsing function as some library function,
>>>>> I do not see any issue.
>>>>> If any exported symbol is available for this then any nvmem provider
>>>>> could use it.
>>>>>
>>>>> --srini
>>>>>
>> Hi Srinivas,
>>
>> Can I note here that I would like to parse
>> TLV data from an SPI-NOR device to NVMEM cells.
>> The same general use case (getting mac-address from OEM data).
>>
>> Was planning to base my work on this series, as well as
>> https://lore.kernel.org/all/20210908100257.17833-1-qiangqing.zhang@nxp.com/
>> (thanks for pointing that out Srinivas)
>>
>> Cheers,
> What about at least to have just one call in core.c to make it a bit
> de-coupled, like:

Why do you want to decouple this? the provider driver should be very 
well aware of the format the data layout.

Its fine to an extent to adding parse_cells() callback in nvmem_config.

> 
> core.c
> 
> struct nvmem_device *nvmem_register(const struct nvmem_config *config)
> {
> ...
>           rval = nvmem_add_cells_from_table(nvmem);
>           if (rval)
>                   goto err_remove_cells;
> 
> +        rval = nvmem_parse_cells(nvmem, of);
> +        if (rval) {
> +        /* err handling */
> +        }
> +
>           rval = nvmem_add_cells_from_of(nvmem);
>           if (rval)
>                   goto err_remove_cells;
> 
>           blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
> 
>           return nvmem;
> 
> ...
> 
> }
> 

> somewhere in nvmem-parser.c:

However this is totally over kill.

> 
> /* retreive parser name from of_node and call appropriate function to parse
>     non-fixed cells and update via of_update */

This is completely provider drivers job, nothing nvmem core should worry 
about.

If you have concern of having code duplicated then we could make some of 
the common functions as library functions, But it still is within the 
scope of provider drivers.

--srini

> int nvmem_parse_cells(struct nvmem_device *nvmem, struct device_node *of_node)
> {
>      ...
> }
> 
> ?


> 
> Regards,